CT vs USS in the diagnosis of acute appendicitis
Date First Published:
September 18, 2006
Last Updated:
September 18, 2006
Report by:
Mr. Abel Devadass, Senior House Officer (Causeway Hospital, Londonderry)
Search checked by:
Mr. Jagannath Sherigar, Causeway Hospital, Londonderry
Three-Part Question:
[In patients presenting with symptoms suggestive of acute appendicitis] is [CT or Ultrasound better] in [confirming the diagnosis of acute appendicitis]?
Clinical Scenario:
A young girl presents in the emergency department with right iliac fossa pain, anorexia, nausea and vomiting for the past 12hours. On examination she has significant right iliac fossa tenderness but no rebound or guarding. Her temperature is 37.3„aC and the inflammatory markers are normal. You are not entirely certain if she has acute appendicitis and would not like her to go through an unnecessary operation. You are wondering whether Ultrasound or CT is better in confirming the diagnosis of acute appendicitis.
Search Strategy:
The Pubmed database from 1950-2006 was searched (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed)
Search Details:
The terms used were [acute appendicitis] AND [Ultrasound or CT] AND [diagnosis].
Outcome:
The search result yielded 887 articles. The search was then narrowed down to 552 articles by excluding non-English articles and articles with no abstracts. Among these 552 articles, articles not directly in relevance to the 3-part question were excluded. The remaining 8 articles are summarised below.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| 'Comparison of US and Unenhanced Multi-Detector Row CT in Patients Suspected of Having Acute Appendicitis'. Keyzer C et al 2005 Belgium | 94 patients aged 16-81 years. | Prospective patient study | Accuracy of USS = 84% ; Accuracy of CT = 90% | No difference in diagnostic performance | Paediatric population not included |
| 'Appendiceal Imaging : Which Test is Best?' Blebea JS, Meilstrup JW and Wise SW 2003 USA | 100 adult patients | Prospective patient study | Accuracy of USS = 73%-75% ; Accuracy of CT = 93% | CT is the best initial exam for suspected appendicitis in the adult pt. | Paediatric population not included |
| ' Comparison of CT and Sonography in the Diagnosis of Acute Appendicitis : A Blinded Prospective Study' Poortman P et al 2003 Netherlands | 199 patients aged 3-89years | Prospective patient study | Accuracy of USS = 78% ; Accuracy of CT = 78% | CT was not superior to USS in the diagnosis of acute appendicitis | CT scans evaluated by less experienced radiology staff. Use of non-helical CT |
| 'Comparative Assessment of CT and Sonographic Techniques for Appendiceal Imaging' Wise SW et al. 2001 USA | 100 patients >18yrs old | Prospective patient study | Accuracy of USS = 74-76% ; Accuracy of CT = 87-93% | CT had significantly better diagnostic performance than sonography | Paediatric population not included |
| 'Suspected Acute Appendicitis : Is Ultrasonography or Computed Tomography the Preferred Imaging Technique?' Pickuth D, Heywang-Kobrunner S and Spielmann RP 2000 Germany | 120 patients aged 8-81yrs. | Prospective study | Sensitivity of USS = 87%, Sensitivity of CT = 95% ; Specificity of USS = 74%, Specificity of CT 89% | Unenhanced spiral CT is more accurate than USS in patients suspected of having acute appendicitis | Only equivocal cases were imaged |
| 'A Prospective Trial of Computed Tomography and Ultrasonography for Diagnosing Appendicitis in the Atypical Patient' Horton MD, Counter SF, Florence MG and Hart MJ 2000 USA | 89 patients aged 18-65 years | Prospective randomised study | Sensitivity of USS = 76%, Sensitivity of CT = 97% ; Specificity of USS = 90%, Specificity of CT = 100% | Non-contrast CT scan is the superior diagnostic modality | Paediatric population not included. |
| 'Computed Tomography in the Diagnosis of Equivocal Appendicitis'. Cho CS, Buckingham JM, Pierce M and Hardman DT 1999 Australia | 51 patients aged 13-80 years | Retrospective review | Accuracy of USS = 68% ; Accuracy of CT = 97% | CT can be used to improve the accuracy of diagnosis of obscure RIF pain | Small sample size Retrospective review |
| 'Acute Appendicitis : CT and US Correlation in 100 patients' Balthazar EJ et al. 1994 USA | 100 patients aged 15-82years . | Prospective study. | Accuracy of USS = 83% ; Accuracy of CT = 94% | CT was superior to USS in evaluating patients suspected of having acute appendicitis. | Paediatric population not included. |
Author Commentary:
Most of these studies did not include paediatric patients. Studies that suggested CT superiority employed helical CT. The majority of these studies did not find any significant benefit in the use of intravenous or rectal contrast material during CT. USS accuracy seems to be strongly dependent on operator experience and skill.
Bottom Line:
Helical CT without contrast is more accurate than Sonography in the diagnosis of acute appendicitis.
References:
- Keyzer C et al. 'Comparison of US and Unenhanced Multi-Detector Row CT in Patients Suspected of Having Acute Appendicitis'.
- Blebea JS, Meilstrup JW and Wise SW. 'Appendiceal Imaging : Which Test is Best?'
- Poortman P et al. ' Comparison of CT and Sonography in the Diagnosis of Acute Appendicitis : A Blinded Prospective Study'
- Wise SW et al.. 'Comparative Assessment of CT and Sonographic Techniques for Appendiceal Imaging'
- Pickuth D, Heywang-Kobrunner S and Spielmann RP. 'Suspected Acute Appendicitis : Is Ultrasonography or Computed Tomography the Preferred Imaging Technique?'
- Horton MD, Counter SF, Florence MG and Hart MJ. 'A Prospective Trial of Computed Tomography and Ultrasonography for Diagnosing Appendicitis in the Atypical Patient'
- Cho CS, Buckingham JM, Pierce M and Hardman DT. 'Computed Tomography in the Diagnosis of Equivocal Appendicitis'.
- Balthazar EJ et al.. 'Acute Appendicitis : CT and US Correlation in 100 patients'